This application proposes development of the ASI-MV-CAT, a Computerized Adaptive Testing edition of Inflexxion's popular Addiction Severity Index-Multimedia Version.net (ASI- MV.net). Despite its substantial commercial success, the current version of the ASI-MV.net does not meet all the assessment and treatment needs of administrators, researchers, and clinicians working in the substance abuse area. In many settings, the detailed nature of the data collected and the length of the assessment are unnecessary and can be unduly burdensome. Instead, more quickly obtained summary scores that characterize an individual's overall need for treatment and general level of functioning in key areas is all that is required. Development of the ASI-MV-CAT is intended to meet this need. Based on the principles of Item Response Theory (IRT), the full-scale ASI-MV-CAT will consist of a quick screening test that provides a "Yes/No" answer in regard to "need for treatment," as well as a broad-based-abilities assessment that provides full composite and severity scores for all seven ASI domains. In obtaining these scores, administration time can potentially be reduced by 50% to 80%, while simultaneously exceeding the psychometric performance of the traditional assessment approach. In Phase I, we will showcase the proposed IRT-based scale development methodologies and Inflexxion's overall technical capacities by focusing exclusively on the development and preliminary evaluation of one ASI subscale. In Phase II, similar methodologies will be used to develop the full version of the ASI-MV-CAT, which will then be subject to an extensive field test of its reliability and validity. The Addiction Severity Index (ASI) is one of the most commonly used substance abuse assessment tools, yet its administration can be unnecessarily long and burdensome in many situations, such as those involving population screening, treatment planning, and research. The present study will develop a Computerized Adaptive Testing (CAT) version of the ASI that should significantly reduce the time of administration, while simultaneously improving its accuracy. The availability of this new tool should enhance the quality and reduce the cost of research and treatment in the substance abuse area. [unreadable] [unreadable] [unreadable] [unreadable]